U.S. Pat. NO. 2,099,873 discloses a machine for electrolytically recovering metal, e.g. from a chromium-containing solution, using a cathode formed of a flexible metal belt. The belt moves around a large drum and a number of deflecting rollers arranged adjacent to the drum. The drum is supported by a shaft extending across the level of the solution and is partly submerged in the chromium-containing solution. For the purpose of recovering metal, the drum is constantly rotated so that the belt cathode moves continuously around the drum and the deflecting rollers. A curved anode arranged eccentrically to the drum axis runs at a small distance to the surface of the drum section submerged in the solution and the belt cathode moving over the drum.
When the belt cathode moving out of the solution leaves the periphery of the drum, it extends in horizontal direction to the first deflecting roller, is then guided downwards and, moving over further deflecting rollers arranged in a separate water tank outside the tank holding the chromium-containing solution, returned to the drum.
Due to the fact that the belt cathode is sharply bent while moving over the deflecting rollers, most of the metal having deposited on the flexible belt cathode is released therefrom and collected in the water tank or in a foraminous container nested therein. Any residual particles still adhering to the belt are removed by two scrapers contacting the belt.
The large diameter and the width of the drum are required to obtain a peripheral surface as large as possible because only a portion is submerged in the solution. The belt cathode is dimensioned such that the area covering the submerged peripheral section of the drum is of substantially the same size as the submerged section. As a result, there is always a fairly large deposition surface of the arcuate anode facing the belt cathode contacting the rotating drum.
Due to the above mentioned design features, however, the known metal recovery machine has exceptionally large dimensions. Supporting and driving mechanisms of the amply dimensioned drum are technically sophisticated and expensive. Moreover, removal of the deposited metal is very complicated. Also, due to the continuous movement of the belt cathode, the amount of metal deposited is very small.